Heterosis–Genetic Basis and Utilization for Improvement of Dairy Cattle: A Review

The phenomenon in which progeny of crosses between inbred lines or purebred populations are better than the expected average of the two populations or lines for a particular trait is known as heterosis. Utilization of heterosis is the main goal of crossbreeding. The amount of heterosis maintained in a herd depends on the type of crossbreeding system selected for breeding. Heterosis includes greater viability, faster growth rate and greater milk production in dairy cattle. The genetic basis of heterosis is nonadditive gene action (dominance, overdominance, pseudo-overdominance, and epistasis). The main requirements for heterosis are there must be genetic diversity between the breeds crossed and there must be some nonadditive gene effects present for the particular trait involved. No heterosis was observed for traits governed by additive gene action. However, it tends to be greatest for traits with low heritability and least for traits with high heritability in nature. Traits of low heritability (reproductive traits) are generally most benefited from heterosis as compare to high heritability (growth rate). They can be improved through the adequate use of crossbreeding systems. Keywords: Crossbreeding, heterosis, cattle Cite this Article Kumar M, Ratwan P,  Kumar A. Heterosis–Genetic Basis and Utilization for Improvement of Dairy Cattle: A Review. Research & Reviews: Journal of Dairy Science and Technology . 2016; 5(2): 40–50p.